The Body Surface Area (BSA) Calculator estimates the total surface area of the human body using your height and weight. This calculator uses the Mosteller formula, a simple and widely used method for estimating BSA.
BSA is commonly used in healthcare settings for calculations such as certain medication doses, fluid management, and other clinical measurements. The result is an estimate and should not be used alone to make medical decisions.
The BSA Calculator requires two measurements:
The calculator converts your height to centimeters (cm) and your weight to kilograms (kg). It then applies the Mosteller formula to calculate your estimated body surface area.
The result is displayed in square meters (m²).
For example, a person who is 170 cm tall and weighs 70 kg has an estimated BSA of approximately 1.82 m².
This calculator uses the Mosteller formula:
BSA (m²) = √[(Height (cm) × Weight (kg)) / 3600]
Where:
The Mosteller formula is commonly used because it is simple and requires only height and weight.
Height: Your body height. The calculator accepts height in feet, inches, centimeters, or meters and converts it to centimeters before calculating BSA.
Weight: Your body weight. The calculator accepts weight in kilograms, pounds, US tons, or ounces and converts it to kilograms before applying the formula.
BSA: Your estimated body surface area, expressed in square meters (m²).
Suppose a person has:
Using the Mosteller formula:
BSA = √[(170 × 70) / 3600]
First, multiply the height by the weight:
170 × 70 = 11,900
Then divide by 3,600:
11,900 ÷ 3,600 = 3.3056
Finally, calculate the square root:
√3.3056 ≈ 1.82 m²
Estimated BSA = 1.82 m²
This result is an estimate based on the person's height and weight.
BSA is expressed in square meters (m²) and represents an estimate of the body's total external surface area.
For many adults, BSA values commonly fall roughly between 1.5 and 2.2 m², although the actual value varies depending on body size, height, weight, age, and other factors.
There is no single BSA value that is considered ideal for everyone.
BSA can be useful in clinical settings because some medical calculations, including certain medication doses and physiological measurements, may use BSA instead of body weight alone.
Important: If your BSA is being used for medication dosing or medical treatment, follow the calculation method and instructions provided by your healthcare professional. Different clinical situations may use different BSA formulas or dosing guidelines.
1. Selecting the wrong height unit
Make sure you select the correct unit for your height. For example, entering 170 while selecting meters instead of centimeters will produce an incorrect result.
2. Selecting the wrong weight unit
Make sure you select kg when entering kilograms and pounds when entering pounds.
3. Confusing pounds with kilograms
Pounds and kilograms are different units. For example, 154 lb is approximately 70 kg. Selecting the wrong unit can significantly change the calculated BSA.
4. Entering height incorrectly
Pay attention to the selected height unit. If you enter your height in feet, make sure the value matches the unit selected in the calculator.
5. Rounding measurements too early
For a more accurate estimate, enter your height and weight as accurately as possible instead of heavily rounding them before calculation.
6. Assuming BSA is a diagnosis
BSA is an estimated body measurement. It does not diagnose a disease or determine whether someone is healthy.
Mosteller RD. Simplified Calculation of Body-Surface Area. New England Journal of Medicine. 1987.
Du Bois D, Du Bois EF. A Formula to Estimate the Approximate Surface Area if Height and Weight Be Known. Archives of Internal Medicine. 1916.
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